Materials offering varying degrees of such protection for different applications are known, for example those used in items such as bullet resistant vests, surgical and garden gloves etc. The principal requirement of such materials is that they safely perform the function for which they are intended, i.e. that they afford at least the required degree of protection. With garden gloves for example, the gloves are intended to offer the wearer sufficient protection against injury from for example thorns. With a bullet resistant vest, clearly the vest must be able to prevent penetration from bullets. In all cases, the item should ideally not detrimentally affect the activities of the wearer and be as comfortable as possible to wear. Thus for garden gloves, as well as providing protection to the wearer, the gloves should be sufficiently flexible and offer adequate sensitivity so as not to inhibit the gardening activities of the wearer.
The flexibility and sensitivity of a garment will depend on the characteristics and dimensions of the material from which it is made. Generally speaking a thicker material will offer less flexibility and sensitivity than a thinner material.
In certain applications there is therefore often a compromise between protection and flexibility/sensitivity with regard to the material thickness. For example for surgical gloves the requirements of flexibility and sensitiveness are paramount, bearing in mind the delicate operations a surgeon has to perform. Ideally therefore the material should be as thin as possible.
In this connection most surgical gloves currently in use are made from latex, an elastic material which can be made sufficiently thin so as to offer the required degree of flexibility and sensitivity for delicate operative techniques.
The choice of latex for surgeon's gloves has in the past arisen predominantly out of the flexibility and sensitivity necessities and has in a protection point of view been in the patient's rather than the surgeon's interests, i.e. for the purpose of maintaining as sterile conditions as possible for the patient so as to minimise the risks of infection. However the use of surgical gloves is now also becoming vital in the role of providing protection for the surgeon against accidental self inflicted injuries that regularly occur by way of so-called `needle stick` accidents. Such accidents occur for example when a surgeon inadvertently stabs himself or herself with a needle or scalpel blade that is being used. Protection in the form of gloves is thus utilised by surgeons and other health workers to reduce the risk of infection to themselves in such circumstances.
The puncture resistance of latex gloves is however minimal such that with current concerns in relation to accidental infection of diseases such as HIV (human immunodefeciency virus) and Hepatitis A,B,C,D and E and in the absence of any better alternative, surgeons are often `double gloving`, namely wearing two latex gloves on each hand, one on top of another, to reduce the risks of glove puncture and thus infection. Clearly the use of two gloves in this way can only detrimentally lessen the flexibility and touch sensitivity of the glove to the wearer.
There are known materials in the field of armoured clothing, for example as disclosed in co-pending application No. WO 93/21492, which are puncture resistant and are directed to affording protection from projectiles, e.g. bullets. However such materials are generally heavy duty and cannot by virtue of their interlocking construction provide the degree of flexibility required for delicate applications.
There are also materials available which are primarily cut or slash resistant in that they offer the wearer of a garment made from such a material increased protection against cuts and slashes made across the material. This is useful for providing protection against, say scalpel wounds. Such materials are however not notably puncture resistant.
US-A-5200263 and US-A-5138719 both disclose puncture resistant materials which comprise a plurality of flat platelets formed either of metal discs or carbon fibres which are disposed within the material. Such materials are made by dipping a former into a polymeric material, for example, a latex usually used for glove formation into which has been disposed a plurality of platelets. By virtue of the dipping procedure the platelets to a certain extent orientate in the latex material, but always at the junction of overlaying layers of latex.
Materials such as those disclosed in these citations do in fact increase penetration resistance to needle stick but not to the necessary degree, due possibly to a failure of the dipping process to reliably align the platelets, particularly when these are of small size, parallel to the plane of the material.
Latex gloves such as those commonly used by surgeons have relatively low puncture resistance. As shown in FIG. 5 which follows, for example, single glove thicknesses have a penetration resistance of about 20 grams and double gloves tend to have a penetration resistance of 40 grams. By way of comparison, leather with an equivalent thickness will have a static load resistance of a little over 200 grams while a Medak glove which is some six times thicker and hence is quite unsuited to surgical use other than for orthopaedic procedures will resist a little over 600 grams static load.